无法从 Azure Function 连接到 Azure Cosmos DB。 获取“Microsoft.Azure.Cosmos.Direct：Object 引用未设置为 object 的实例

Question

Got a.Net code from Udemy course and ran in my local. Wrote an Azure Function which connects to Azure Cosmos DB and creates an item. But not getting connected to Azure Cosmos DB. See below the code and error. Appreciate any help. In the debug, found out some issue with the line

_container.CreateItemAsync(_blobdetails, newPartitionKey(_message.VideoName)).GetAwaiter().GetResult();

Code :

using System;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;
using Azure.Messaging.ServiceBus;
using Azure.Storage.Blobs;
using Azure.Storage.Blobs.Models;
using Microsoft.Azure.Cosmos;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;
using Microsoft.Extensions.Logging;

namespace ReceiveMessages
{
    public static class Process
    {
        private static string blob_connection_string = "<blob connection string>";
        private static string source_container_name = "unprocessed";
        private static string destination_container_name = "processed";

        private static readonly string _connection_string = "<cosmos connection string>";
        private static readonly string _database_name = "appdb";
        private static readonly string _container_name = "video";

        [FunctionName("ProcessVideos")]
        public static async Task Run([ServiceBusTrigger("videoqueue", Connection = "connection")]ServiceBusReceivedMessage myQueueItem, ILogger log)
        {
            try
            {
                ReceivedMessage _message = JsonSerializer.Deserialize<ReceivedMessage>(Encoding.UTF8.GetString(myQueueItem.Body));

                BlobServiceClient _client = new BlobServiceClient(blob_connection_string);
                BlobContainerClient _source_container_client = _client.GetBlobContainerClient(source_container_name);
                BlobClient _source_blob_client = _source_container_client.GetBlobClient(_message.VideoName);

                BlobContainerClient _destination_container_client = _client.GetBlobContainerClient(destination_container_name);
                BlobClient _destination_blob_client = _destination_container_client.GetBlobClient(_message.VideoName);

                CosmosClient _cosmosclient = new CosmosClient(_connection_string, new CosmosClientOptions());
                Container _container = _cosmosclient.GetContainer(_database_name, _container_name);

                BlobDownloadInfo _info = _source_blob_client.Download();
                // Copy the blob to the destination container
                await _destination_blob_client.StartCopyFromUriAsync(_source_blob_client.Uri);

                log.LogInformation(_info.Details.LastModified.ToString());
                log.LogInformation(_info.ContentLength.ToString());

                BlobDetails _blobdetails = new BlobDetails();
                _blobdetails.BlobName = _message.VideoName;
                _blobdetails.BlobLocation = "https://videostorage100.blob.core.windows.net/processed/" + _message.VideoName;
                _blobdetails.ContentLength = _info.ContentLength.ToString();
                _blobdetails.LastModified = _info.Details.LastModified.ToString();
                _blobdetails.id = Guid.NewGuid().ToString();

                _container.CreateItemAsync(_blobdetails, new PartitionKey(_message.VideoName)).GetAwaiter().GetResult();
                Console.WriteLine("Item created");

                // Delete the blob from the unprocessed container
                _source_blob_client.Delete();
                // Add the details of the blob to an Azure Cosmos DB account

            }
            catch (Exception ex)
            {
                string s = ex.Message;
            }



        }
    }
}


    

* Executed 'ProcessVideos' (Failed, Id=53b3d0b2-d46a-4ba9-bf26-d8de76af0bce, Duration=41001ms)
[2022-03-19T23:07:25.845Z] Executed 'ProcessVideos' (Failed, Id=48b50a3d-f69f-436f-accf-5140c3d7f8a0, Duration=41001ms)
[2022-03-19T23:07:25.854Z] System.Private.CoreLib: Exception while executing function: ProcessVideos. Microsoft.Azure.Cosmos.Direct: Object reference not set to an instance of an object.{"name":"CreateItemAsync","id":"c16e23cd-badc-4f0b-a940-3fac7f52c4f7","caller info":{"member":"OperationHelperWithRootTraceAsync","file":"ClientContextCore.cs","line":219},"start time":"11:06:46:894","duration in milliseconds":36808.7271,"data":{"Client Configuration":{"Client Created Time Utc":"2022-03-19T23:06:45.5706176Z","NumberOfClientsCreated":3,"User Agent":"cosmos-netstandard-sdk/3.19.0|3.19.1|08|X64|Microsoft Windows 10.0.19043|.NET Core 3.1.20|N|","ConnectionConfig":{"gw":"(cps:50, urto:10, p:False, httpf: False)","rntbd":"(cto: 5, icto: -1, mrpc: 30, mcpe: 65535, erd: False, pr: ReuseUnicastPort)","other":"(ed:False, be:False)"},"ConsistencyConfig":"(consistency: NotSet, prgns:[])"}},"children":[{"name":"ItemSerialize","id":"647e3fbb-bd9f-4b12-9367-3ed1f6c4d436","caller info":{"member":"ExtractPartitionKeyAndProcessItemStreamAsync","file":"ContainerCore.Items.cs","line":931},"start time":"11:06:46:921","duration in milliseconds":20.2124},{"name":"Microsoft.Azure.Cosmos.Handlers.RequestInvokerHandler","id":"23650859-deb4-44e1-a696-daeeab7564c8","start time":"11:06:47:893","duration in milliseconds":35799.6699,"children":[{"name":"Microsoft.Azure.Cosmos.Handlers.DiagnosticsHandler","id":"f18265a9-2a93-46c8-aa05-78b69ed30086","start time":"11:06:47:927","duration in milliseconds":35763.5861,"data":{"CPU Load History":{"CPU History":"(2022-03-19T23:06:47.9376170Z 38.049)"}},"children":[{"name":"Microsoft.Azure.Cosmos.Handlers.RetryHandler","id":"876ad64c-0dc3-42a2-9a47-4054ec301b57","start time":"11:06:47:945","duration in milliseconds":35744.6099,"children":[{"name":"Microsoft.Azure.Cosmos.Handlers.RouterHandler","id":"01ca2b19-39c0-477d-ad85-f930397e682a","start time":"11:06:47:954","duration in milliseconds":35729.8987,"children":[{"name":"Microsoft.Azure.Cosmos.Handlers.TransportHandler","id":"e372af16-b68c-438d-9ae1-2fdaad2d5f23","start time":"11:06:47:955","duration in milliseconds":35720.3525,"children":[{"name":"Microsoft.Azure.Documents.ServerStoreModel Transport Request","id":"9995478e-5933-4b21-8c08-cf03501ebe03","caller info":{"member":"ProcessMessageAsync","file":"TransportHandler.cs","line":109},"start time":"11:06:47:963","duration in milliseconds":35704.0196,"data":{"Client Side Request Stats":{"Id":"AggregatedClientSideRequestStatistics","ContactedReplicas":[{"Count":1,"Uri":"rntbd://cdb-ms-prod-westus1-fd76.documents.azure.com:14059/apps/0152c08e-edca-4977-bca0-40bb4325ee70/services/117845df-eb50-4f9a-8f97-0a5981cfeaae/partitions/1e48d158-7844-4a7c-89a0-aa99c17adcb8/replicas/132920901445077053s/"},{"Count":1,"Uri":"rntbd://cdb-ms-prod-westus1-fd76.documents.azure.com:14352/apps/0152c08e-edca-4977-bca0-40bb4325ee70/services/117845df-eb50-4f9a-8f97-0a5981cfeaae/partitions/1e48d158-7844-4a7c-89a0-aa99c17adcb8/replicas/132920901532421814s/"},{"Count":1,"Uri":"rntbd://cdb-ms-prod-westus1-fd76.documents.azure.com:14095/apps/0152c08e-edca-4977-bca0-40bb4325ee70/services/117845df-eb50-4f9a-8f97-0a5981cfeaae/partitions/1e48d158-7844-4a7c-89a0-aa99c17adcb8/replicas/132920901532421816s/"}],"RegionsContacted":["https://videodbupdate-westus.documents.azure.com/"],"FailedReplicas":[],"AddressResolutionStatistics":[{"StartTimeUTC":"2022-03-19T23:06:48.3431877Z","EndTimeUTC":"2022-03-19T23:06:48.4598190Z","TargetEndpoint":"https://videodbupdate-westus.documents.azure.com//addresses/?$resolveFor=dbs%2fHdYjAA%3d%3d%2fcolls%2fHdYjAIRIK9s%3d%2fdocs&$filter=protocol eq rntbd&$partitionKeyRangeIds=0"},{"StartTimeUTC":"2022-03-19T23:06:54.7678280Z","EndTimeUTC":"2022-03-19T23:06:54.8820135Z","TargetEndpoint":"https://videodbupdate-westus.documents.azure.com//addresses/?$resolveFor=dbs%2fHdYjAA%3d%3d%2fcolls%2fHdYjAIRIK9s%3d%2fdocs&$filter=protocol eq rntbd&$partitionKeyRangeIds=0"},{"StartTimeUTC":"2022-03-19T23:07:01.6288211Z","EndTimeUTC":"2022-03-19T23:07:01.7399788Z","TargetEndpoint":"https://videodbupdate-westus.documents.azure.com//addresses/?$resolveFor=dbs%2fHdYjAA%3d%3d%2fcolls%2fHdYjAIRIK9s%3d%2fdocs&$filter=protocol eq rntbd&$partitionKeyRangeIds=0"},{"StartTimeUTC":"2022-03-19T23:07:09.6372169Z","EndTimeUTC":"2022-03-19T23:07:09.7484346Z","TargetEndpoint":"https://videodbupdate-westus.documents.azure.com//addresses/?$resolveFor=dbs%2fHdYjAA%3d%3d%2fcolls%2fHdYjAIRIK9s%3d%2fdocs&$filter=protocol eq rntbd&$partitionKeyRangeIds=0"},{"StartTimeUTC":"2022-03-19T23:07:17.9939496Z","EndTimeUTC":"2022-03-19T23:07:18.1025134Z","TargetEndpoint":"https://videodbupdate-westus.documents.azure.com//addresses/?$resolveFor=dbs%2fHdYjAA%3d%3d%2fcolls%2fHdYjAIRIK9s%3d%2fdocs&$filter=protocol eq rntbd&$partitionKeyRangeIds=0"}],"*

*[2022-03-19T23:07:25.848Z] System.Private.CoreLib: Exception while executing function: ProcessVideos. Microsoft.Azure.Cosmos.Client: Response status code does not indicate success: ServiceUnavailable (503); Substatus: 0; ActivityId: 349d6ef1-4696-4ec8-88c9-5913129164ec; Reason: (Service is currently unavailable. More info: https://aka.ms/cosmosdb-tsg-service-unavailable
[2022-03-19T23:07:26.012Z] System.Private.CoreLib: Exception while executing function: ProcessVideos. Microsoft.Azure.Cosmos.Client: Response status code does not indicate success: ServiceUnavailable (503); Substatus: 0; ActivityId: 40f51724-2bf3-46b2-ac99-c9030aed41c6; Reason: (Service is currently unavailable. More info: https://aka.ms/cosmosdb-tsg-service-unavailable
[2022-03-19T23:07:26.040Z] ActivityId: 349d6ef1-4696-4ec8-88c9-5913129164ec, Microsoft.Azure.Cosmos.Tracing.TraceData.ClientSideRequestStatisticsTraceDatum, Windows/10.0.19043 cosmos-netstandard-sdk/3.19.1);. Microsoft.Azure.Cosmos.Direct: Message: The requested resource is no longer available at the server.*

Answer 1

This was fixed in SDK 3.20: https://github.com/Azure/azure-cosmos-do.net-v3/blob/master/changelog.md#-3200---2021-06-21

Please upgrade to the recommended version to get this and other fixes.

More fixes

You are creating a client (both Blob and Cosmos) per Function execution, that goes against the recommendations and will bring problems as the number of queue messages increase, please follow https://learn.microsoft.com/azure/azure-functions/manage-connections?tabs=csharp#static-clients and use Singleton/static instances. We have a complete example on how to use DI and Functions with the CosmosClient at https://github.com/Azure/azure-cosmos-do.net-v3/tree/master/Microsoft.Azure.Cosmos.Samples/Usage/AzureFunctions .

Also, do not block threads, since your Function is already async, do await _container.CreateItemAsync(_blobdetails, new PartitionKey(_message.VideoName)) instead.

These 2 points is what will generate these Service Unavailable errors in most cases.

ALSO VERY IMPORTANT, YOUR POST CONTAINED SERVICE KEYS AND CONNECTIONSTRINGS (I EDITED TO REMOVE THEM BUT THEY WERE ALREADY EXPOSED), ROTATE THEM IMMEDIATELY